It’s time for the candidate to level with voters on his tax and economic plans

In school, math students have to show how they arrive at the answer to a problem. Doing so demonstrates that they understand the equation, that their logic is sound and that they didn’t just take a wild guess.

But Republican presidential candidate Mitt Romney has yet to show us the math of how he’ll engineer $8 trillion in tax breaks and increased defense spending and still be able to reduce the nation’s deficit. We’re supposed to wait until he’s elected before he shares the details. That’s a gamble that voters shouldn’t take.

It’s pure arrogance for Romney to suggest that voters don’t need to see the details— that they should just trust him. When asked about it at Tuesday’s debate, Romney simply insisted that his numbers add up.

Not so, according to the nonpartisan Tax Policy Center, which concluded that Romney’s plan either blows up the budget deficit or forces the middle class to shoulder a greater tax burden to pay for the plan.

Romney’s plan calls not only for a 20-percent reduction in marginal tax rates, but would also eliminate the estate tax and alternative minimum tax. According to the center, that brings the total of his tax plan to $5 trillion. Add another $1 trillion for his proposal to make the Bush tax cuts permanent and the figure rises to $6 trillion. His plan to increase defense spending adds another $2 trillion to the tab.

How do you pay for such a such a colossal combination of tax cuts and higher spending? Simple, says Romney, you close tax loopholes to capture more revenue. The problem, however, is there aren’t enough loopholes to close to cover the cost of the tax cuts, let alone the increased spending on defense.

Even if there were enough loopholes and tax breaks, closing them would be a major challenge. The “loopholes” on the table include the tax deduction for mortgage interest, which disproportionately affects the middle and working classes. Other potential tax deductions that could be eliminated are child tax credits or health care credits. Tax deductions, which affect a broad number of people, are bound to encounter resistance.

And while Congress may be willing to drop tax rates, it will be considerably more challenging to slash tax deductions, each with its own set of stakeholders and lobbyists to challenge their elimination.

His tax plan isn’t the only area where Romney seems to have plucked numbers from thin air without justification. His claim that his policies would create 12 million jobs over the next four years is equally baseless.

Seven million of those jobs would be created under his tax plan, according to the candidate. But the analysis he cites as evidence for his claim predicts those jobs would be created over 10 years, not four as Romney claims.

The remainder of his jobs numbers are equally dubious. For instance, Romney’s claim that his energy policies would create three million jobs appears to be largely based on a Citigroup Global Markets study that did not even evaluate Romney’s policies. Instead, the report predicted 2.7 million to 3.6 million jobs would be created over the next eight years, largely because of trends and policies already adopted — including tougher fuel efficiency standards that Romney has belittled and said he would reverse.

His claim to produce two million jobs by cracking down on China is also shaky.

The figure comes from a 2011 International Trade Commission report, which estimated that there could be a gain of 2.1 million jobs if China stopped infringing on U.S. intellectual property rights. The estimate is highly conditional and pegged to the job market in 2011, when there was high unemployment. It’s also worth noting that the report does not examine any of Romney’s proposed policies, nor does Romney indicate how he’d prevent China from infringing on things like patents and copyrights.

There’s an old saying that figures don’t lie, but liars can figure. If Romney can demonstrate that his math adds up, he has an obligation to share it with voters before they entrust him with the national budget. After all, we expect that much from students. Shouldn’t we demand the same from someone who wants to be president?